UMTS (Universal Mobile Telecommunications System) is the 3rd generation mobile communication system of the radio technology using WCDMA. In the system architecture of the UMTS terrestrial radio access network (UTRAN) shown in FIG. 1, a radio network controller (RNC) is connected to a core network via an Iu interface, the RNCs are interconnected via an Iur interface, and one RNC is connected to one or more Node Bs via an Iub interface. A Node B contains one or more cells, the cell being a basic unit to which a user equipment (UE) has wireless access (not shown), wherein a radio interface between the UE and the UTRAN is a Uu interface (not shown).
In the protocol documents of the standardization organization 3GPP (the 3rd Generation Partnership Project) of the UMTS, there mainly are TS25.2XX, TS25.3XX and other serial specifications relevant to the UMTS radio interface protocol. In the UMTS radio interface protocol architecture as shown in FIG. 2, the bottom layer is a physical (PHY) layer, and in a control plane, above the physical layer are a media access control (MAC) layer, a radio link control (RLC) layer and a radio resource control (RRC) layer, respectively; in a user plane, the radio interface protocol consists of the physical layer, the MAC layer, the RLC layer and a packet data convergence protocol (PDCP) layer, wherein the PDCP layer is only for a packet-switch (PS) domain. Physical channels are provided by the physical layer, logical channels are provided between the MAC layer and the RLC layer, and transport channels are provided between the MAC layer and the physical layer.
In the UMTS radio access network (UTRAN) of R99, the logical channels of the control type include BCCH (Broadcasting Control Channel), PCCH (Paging Control Channel), DCCH (Dedicated Control Channel), CCCH (Common Control Channel), etc.; the logic channels of the traffic type include DTCH (Dedicated Traffic Channel), CTCH (Common Traffic Channel), etc. Uplink transport channels comprise RACH (Random Access Channel), CPCH (Common Packet Channel), DCH (Dedicated Channel), etc., while downlink transport channels comprise BCH (Broadcast Channel), PCH (Paging Channel), FACH (Forward Access Channel), DSCH (Downlink Shared Channel), and DCH, etc. One of the primary functions of the MAC layer is to map logical channel as transport channel. FIG. 3 shows the mapping relations between downlink logic channels and transport channels.
According to the 3GPP specification including 3GPP TS 25.212, 3GPP TS 25.302 and other documents, a TFI (Transport Format Indication) of each transport channel corresponds to one transport format in a Transport Format Set (TFS) of the transport channel. In each TTI (Transport Time Interval), as illustrated in FIG. 4, an upper layer transports TBs (Transport Blocks) of the respective transport channels to a PHY layer based on a certain Transport Format Combination (TFC); the PHY layer then combines the TFI information from the different transport channels into a TFCI (Transport Format Combination Indication), encodes it and transports it on a TFCI field of the PHY channel; after that, a receiving terminal decodes the TFCI field so as to precisely receive the TBs from the respective transport channels.
In UMTS, the main factor which influences downlink capacity, coverage and other performances is a limited downlink power. The total maximum transmit power of downlinks in a cell is determined by a rated output power of a base station power amplifier, and this power is typically divided into fixed static power, non-schedulable power, and schedulable power, etc., as shown in FIG. 5. The fixed static power is used for downlink common control channels in a cell, such as common piloting, synchronizing, is paging and so forth, and this fixed static power is determined by cell configuration and other parameters; the non-schedulable power is a power occupied by real-time services including conversational type and streaming type services, wherein the real-time service allows the selection of a certain rate, but the rate itself is still required to be constant, so this power is non-schedulable; the schedulable power is mainly used for NRT (Non Real-Time) packet services such as interactive type and background type services, which allows for a dynamic change in the rate, so the power occupied by these services is schedulable.
When utilizing DCHs to transport interactive or background NRT packet data, a total power of DCHs bearing packet services of a plurality of different users forms the above non-schedulable power. However, in the downlink direction of UTRAN, each UE has a DCH functional entity MAC-d corresponding thereto, but the MAC-d entities of different UEs are independent of each other. Therefore, each cell must utilize a chief scheduling unit for conducting combined packet scheduling of all the DCHs in the cell employed for transporting NRT packet data. Nevertheless, the existing downlink packet scheduling technology in the UMTS is mainly aimed at common or shared channels such as FACH/DSCH, etc., and the scheduling of the common or shared type channels can be basically summed up as a problem that a plurality of input data streams shares an output channel with limited bandwidth resources. In practice, as for the familiar scheduling problems in this type of telecommunications, there are a large number of mature and effective algorithms at present, typically such as Round-Robin, WFQ (Weighted Fair Queuing), WF2Q (Worst-case Fair Weighted Fair Queuing) and so forth. Please refer to “H. Zhang, Service disciplines for guaranteed performance service in packet-switching networks, Proceedings of the IEEE, vol. 83, pp. 1374-1396, Oct. 1995”, “V. Bharghavan, S. Lu and T. Nandagopal, Fair queuing in wireless networks: Issues and Approaches, IEEE Personal Communication, Vol. 6, No. 1, pp. 44-53, February 1999”, and other documents.